Azo dyestuff



Patented Nov. 14, 1944 PATENT OFFICE M Azo nms'rurr 1 I Joseph F. Froning, Wilmington, De l., assignor to 1 E. I. du Pont de Nemours & Company, Wilmington,

Del., a corporation of Delaware No Drawing. Application June 12, 1943, Serial No. 490,642

3 Claims.

This invention relates to a scarlet azo dyestufi for cotton fabrics.

The art has need of a scarlet azo dyestufl fast to washing which will discharge more perfectly parts of 5 normal sodium nitrite solution at C. Excess nitrous acid was removed by the addition of sulfamic acid, according to the proc es of Lubs' (U. S. Patent2,160,882) and 135 than the colors used for that purpose at the 5 parts of o-anisidine was added. After stirring present time. In one form of discharge printseveral hours the resulting insoluble monazo ing,- as practiced in the art, cotton iabric is dyed compound was filtered ofi and washed. It was with a selected'color and overprinted with a disthen dissolved with enough sodium hydroxide in charge paste which is applied in a pattern from 2000 parts of water at 50 C. to give 'a slightly a printing roller or in other known ways. The 10 alkaline solution which was clarified with'chardischarge paste destroys the color at the points to which it is applied, and the disintegrated elements of the color are washed out of the fabric.

The effect of the discharge varies widely with different colors, with some being inefifective and with others effective to a high degree. Perfection of discharge it attained only when the discharged cloth has been left without a trace of stain. This condition is but rarelyattained.

It is an object of this invention to prepare an azo color having superior discharge and exceptional fastness to washing. Fastness to washing is particularly important in these colors because of the washin which follows the discharge.

The objects of the invention are accomplished by the preparation of the color represented by the formula: Y

coal. This amino azo compound was then diazotized at C. by the addition of 180 parts of 10 normal hydrochloric acid and 120 parts of 5 normal sodium nitrite solution, and the resulting diazo compound was added at 10 C. to a solution of 130 parts of 1-(3"-amino-phenyl) -5- pyrazolone-B-carboxylic acid and 112 parts of 10 normal sodium-hydroxide solution and 100 parts sodium carbonate in 2000 parts water. The resultin disazo color was salted out at 60 C. and filtered and washed with brine. It was then redissolved in 2000 parts water at 60 C., filtered and treated with 120 parts of 5 normal sodium nitrite solution and 180 parts of 10 normal hydrochloric acid at 15 to 20 C. to form the diazonium compound, which was added at 10 C. to a, solution of 220 parts m-amino-benzoyl-J- on. 0cm 1 O=C N N=N mots-Ooh N=N--(JJH I NSOBS- NHO o- NH: I O=( J0Na which is produced by diazotizing 3-amino-toluacid and 64 parts of 10 normal sodium hydroxide ene-fi-sulfonic acid and coupling it to ortho-, solution and 120 parts sodium carbonate in 2000 anisidine, diazotizing the product and coupling parts water. The resulting trisazo color was it to meta-amino-phenyl-pyrazolone-carboxylic 40 salted out, filtered, and washed with brine. .acid, diazotizing the product and coupling it to When dried and ground, it was a red powder. meta-amino-benzoyl-J-acid. This color has an It dyed cotton cloth a scarlet color. Ten grams additional advant einthat it may be diazotized of this dyed cotton cloth was wet with water on the fiber and coupled to ta-n p ol. The and put into 250 cc. of an aqueous solution of developed color is somewhat stronger. The de- 03 of di t it n 0, v of sulfuric veloped color, when a h W ne or acid and occasionally turned for 20 minutes at neutral dlschar e p E v an excellent room temperature, then removed, rinsed with charge. water and put into 250 cc. of an aqueous solu 'Ihe followin ex p illustrated the v tion of 0.1 g, of beta-naphthol and 0.05 g. oi tion: .sodium hydroxide at room temperature. After Ew mp 20 minutes, the dyed cloth was removed, rinsed 187 parts f t 1 1 m acid and dried. The resulting shade was stronger as t sodium m; was dissolved i 2000 parts than before the treatment with beta-naphthol of water and diazotized by the addition of 250 n had very good fastness to washing. When parts of 10 normal hydrochloric acid and 200 treated w h n utral 01. alkaline discharge pastes,

the developed color was bleached, and an excellent discharge of the color was obtained.

This dye is of particular use where washable cotton or rayon goods are dyed scarlet. A neutral discharge paste may be used satisfactorily to produce a white pattern on a red background. An alkaline discharge paste containing printing colors produce colored patterns on a'red background.

As many apparently widely diiferent embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments thereof except as defined in the appended claims.

' benzdyl-J-acid.

I claim:

1. The scarlet dyestuff represented by the formula 3-amino-toluene-6-sulfonic acid-*orthoanisidine-+meta amino phenyl pyrazolonecarboxylic acidmeta-amino-benzoyl-J-acid.

2. Cotton dyed with the dyestufi of claim 1 diazotized, and developed with beta-naphthol.

3. The process of preparing a scarlet dyestufl which comprises coupling 3-amino-toluene-6- sulfonic acid diazo to ortho-anisidine, diazotizing the product and coupling it to meta-aminophenylpyrazolone carboxylic acid, diazotizing the product and coupling it to meta-amino- JOSEPH F. FRONING. 

